In the process of acquiring seismic data, a crew is typically deployed across several square miles of a survey area positioning cables and seismic receivers while seismic sources move from predetermined point to predetermined point to deliver vibrational seismic energy into the earth. The receivers capture the reflected signals that are recorded and subsequently processed to develop images of geologic structures under the surface.
Occasionally, two crews will end up working survey areas that are sufficiently close that recordings in one survey area will include seismic energy delivered in the other survey area. As both crews try to acquire useful seismic data, both typically end up with obscured data that is difficult to process and unhelpful for resolving the subsurface geology. Typically, when these situations arise, the crews end up time sharing such that only one crew is permitted to deliver seismic energy at any moment in time. While the data is much more useful and valuable, the time for acquiring the data is prolonged and much more costly.
Phase encoded seismic sweeps by sweep vibrators on separate source points, sometimes described as Zenseis® seismic prospecting, increases seismic survey productivity over conventional seismic by acquiring data at several source points at the same time. If two phase encoded surveys are being conducted at the same time in close proximity, as long as the start times for each sweep are reasonably separated and the phase encoding of each crew is optimally tuned, each may generally proceed without time sharing. However, a conventional seismic survey crew receives the phase encoded sweeps as significant noise and, heretofore, have not been able to proceed when another crew is in the area.